Background and aims: Rigorous donor preselection on microbiota level, strict anaerobic processing, and repeated FMT administration were hypothesized to improve FMT induction of remission in UC.
Methods: The RESTORE-UC trial was a multi-centric, double-blind, sham-controlled, randomized trial. Patients with moderate to severe UC (defined by total Mayo 4-10) were randomly allocated to receive four anaerobic-prepared allogenic or autologous donor FMTs. Allogenic donor material was selected after a rigorous screening based on microbial cell count, enterotype, and the abundance of specific genera. The primary endpoint was steroid-free clinical remission (total Mayo ≤2, no sub-score >1) at week 8. A pre-planned futility analysis was performed after 66% (n=72) of intended inclusions (n=108). Quantitative microbiome profiling (n=44) was performed at weeks 0 and 8.
Results: In total, 72 patients were included of which 66 received at least one FMT (allogenic-FMT n=30 and autologous-FMT n=36). At week 8, respectively 3 and 5 patients reached the primary endpoint of steroid-free clinical remission (p=0.72), indicating no treatment difference of at least 5% in favour of allogenic-FMT. Hence, the study was stopped due to futility. Microbiome analysis showed numerically more enterotype transitions upon allogenic-FMT compared to autologous-FMT and more transitions were observed when patients were treated with a different enterotype than their own at baseline (p=0.01). Primary response was associated with lower total Mayo scores, lower bacterial cell counts, and higher Bacteroides 2 prevalence at baseline.
Conclusion: The RESTORE-UC trial did not meet its primary endpoint of increased steroid-free clinical remission at week 8. Further research should additionally consider patient-selection, sterilized sham-control, increased frequency, density, and viability of FMT prior to administration.
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